In the study the results of luminescence spectra investigating and excitation of ceramics luminescence with different Al/Ga ratios, synthesized by irradiating a mixture of initial materials with different prehistories were presented. Mixtures of oxides powders with stoichiometric composition corresponding to Y3AlxGa5-xO12: Ce, where x ranged from 0 to 5, were prepared for synthesis. All initial materials had a purity of no less than ana- lytical grade. The synthesis was carried out under the influence of an electron beam with an energy of 1.4 MeV and a power density of 20 kW/cm2. The yield of the synthesis reaction, the ratio of the sample mass to the mixture, was 90‒95 %. Research has shown that decreasing the Al/Ga ratio results in a shift of the lu- minescence band towards the short-wavelength region of the spectrum. Additionally, the excitation spectrum changes. As the Al/Ga ratio decreases, the excitation band shifts towards the long-wavelength region around 350 nm. The characteristics of luminescence are influenced by the prehistory of the initial materials.

In producing machine parts from the hard materials used today in the military–industrial complex, attainment of the required precision is difficult and sometimes unfeasible unless finishing...

Процесс сушки изоляции обмоток трансформатора оказывает непосредственное влияние на надежность и долговечность трансформатора. Удаление влаги из бумажной изоляции является необходимым этапом в процессе производства трансформаторов. Эффективная функциональность твердой изоляции трансформаторов может снижаться со временем из-за вредного воздействия температуры, влаги и воздуха, что обычно называется старением. Тепло, кислород и остаточная влага ускоряют разрушение целлюлозной изоляции трансформатора, что может привести к преждевременному выходу трансформатора из строя. В процессе сушки изоляции на заводе необходимо обеспечить уровень содержания остаточной влаги ниже 0,5% в объемной твердой изоляции. Основной целью является поддержание высокого уровня полимеризации, который обычно составляет от 1000 до 800. В данной статье исследуются факторы, способствующие деградации целлюлозной изоляции, и проводится анализ различных методов, применяемых на производственном предприятии в Казахстане. Кроме того, в работе экспериментально исследуется влияние вакуума на процесс испарения влаги и частичных разрядов в сравнении с другими методами сушки трансформаторов.

This paper presents an effective approach to reducing noise and vibration levels in ultra-high-voltage (UHV) shunt reactors based on structural optimization and damping techniques. The main sources of vibration are associated with magnetostriction of electrical steel and electromagnetic forces in the magnetic system, which induce structural excitation of the reactor tank. A combined numerical and experimental methodology is employed, including finite element modeling (FEM) of the reactor tank and field measurements of vibration displacement and acoustic noise. In contrast to previous studies focused primarily on material properties, this work emphasizes the role of structural modifications in controlling vibration transmission. The proposed solutions include the use of nitrile butadiene rubber (NBR) damping elements, optimization of the magnetic system geometry, and reinforcement of the tank structure using vertical and horizontal stiffeners. The FEM analysis in the frequency range of 50–150 Hz shows that the maximum displacement amplitude reaches 16.2 μm at the tank bottom and 10.5 μm at the tank walls. Experimental results confirm a reduction in vibration levels to 13 μm and a sound power level of 88 dBA, which meets regulatory requirements. The proposed approach improves the vibroacoustic performance and operational reliability of UHV reactors and can be effectively applied in the design of modern high-voltage power equipment.

(Y_xGd_3−x)(Al_yGa_5−y)O₁₂:Ce and (Lu_xGd_3−x)(Al_yGa_5−y)O₁₂:Ce ceramics were synthesized for the first time by direct exposure of a powerful electron flux to a mixture of the corresponding oxide components. Five-component ceramics were obtained from oxide powders of Y₂O₃, Lu₂O₃, Gd₂O₃, Al₂O₃, Ga₂O₃, and Ce₂O₃ in less than 1 s, without the use of any additional reagents or process stimulants. The average productivity of the synthesis process was approximately 5 g/s. The reaction yield, defined as the mass ratio of the synthesized ceramic to the initial mixture, ranged from 94% to 99%. The synthesized ceramics exhibit photoluminescence when excited by radiation in the 340–450 nm spectral range. The position of the luminescence bands depends on the specific composition, with the emission maxima located within the 525–560 nm range. It is suggested that under high radiation power density, the element exchange rate between the particles of the initial materials is governed by the formation of an ion–electron plasma.

This paper presents the results of studies on Y ₃ Al _x Ga _5-x O ₁₂ : Ce (YAGG:Ce) ceramic phosphors synthesized for the first time using a radiation method. The influence of the Al/Ga ratio on the optical properties of Ce ³ +doped Y ₃ Al _x Ga _5-x O ₁₂ : Ce (YAGG:Ce) garnet phosphors, which are promising for LED light source applications, was investigated. Excitation and photoluminescence spectra of samples with different aluminum and gallium contents at a fixed concentration of Ce ³ + activator ions were analyzed. It was shown that variations in composition lead to changes in the position and shape of the excitation and emission bands, variations in the photoluminescence band width, as well as redistribution of the emission intensity under excitation in the ultraviolet and blue spectral regions. It was found that a decrease in the Al/Ga ratio causes the excitation band to shift toward the longer wavelength region near 340-370 nm, which increases the excitation efficiency when near-ultraviolet and violet LEDs are used. The obtained results confirm the feasibility of using the radiation method for the synthesis of efficient YAGG:Ce phosphors.